Limbic system plays an important role in anxiety and behavior. Single unit activity in the basolateral and dorsomedial portions of the amygdaloid nucleus was recorded with microelectrode in the cat. It was found that both spontaneous and sciatic nerve evoked firing rates of these neurons were decreased by chlordiazepoxide or diazepam. Morphine (sulfate), 0,5 to 2.0 mg/kg i.v., augments the spontaneous and evoked activity. Morphine antagonists, naloxone or levallophan, are not effective, but benzodiazephines are. 1. It is planned to apply morphine, norepinephrine, dopamine (neuro-transmitters) etc. by microiontophoretic technique, not only to localize the direct morphine action on the amygdaloid neurons but also to study its natural neurotransmitters. 2. It is also planned to investigate the unit activity if the other parts of the limbic system, such as the hippocampus, preoptic area, and possibly the hypothalamus. Morphine does not necessarily stimulate all these neurons. Microiontophoretic studies will also be applied to these areas. BIBLIOGRAPHIC REFERENCES: Lee, H.K. and S.C. Wang. Mechanism of morphine-induced , miosis in the dog. J. Pharmacology Exper. Therap. 192: 415-431, 1975. Chou, D.T. and S.C. Wang. Studies on the localization of central cough mechanism and sites of action of antitussive agents. Fed. Proceedings. 34: 349, 1975.